Systems for detecting electrical faults in a vehicle

ABSTRACT

Systems are provided to determine a location of an electrical fault in an electrical system of a vehicle. A test apparatus can include a control unit and a plurality of scan circuits. The control unit is configured to electrically couple the plurality of scan circuits to the electrical system and trigger the plurality of scan circuits to pass electrical signals to the electrical system. Each scan circuit is configured to detect a presence of an electrical fault in the electrical system based on an electrical signal passed. Each scan circuit provides information indicative of a location of the electrical fault in the electrical system, when detected, to the control unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/373,262, filed on 2 Apr. 2019 (now U.S. Patent No. 10,557,885), whichis a continuation of U.S. patent application Ser. No. 14/993,078, filedon 11 Jan. 2016 (now U.S. Pat. No. 10,288,666), which claims priority toU.S. Provisional Application No. 62/101,399, filed on 9 Jan. 2015. Theentire disclosures of these applications are incorporated herein byreference.

BACKGROUND Technical Field

Embodiments of the subject matter disclosed herein relate to detectingelectrical faults in an electrical system of a vehicle.

State of the Art

Modern vehicles include complex control systems and power systems thatinvolve multiple components dispersed throughout the vehicle andextensive wiring interconnecting the components. In operation, a vehiclecan experience significant vibration. Over time, wiring and otherinterconnections of the vehicle can exhibit signs of wear due toreoccurring stresses associated with regular operation. Deterioration ofthe wiring can introduce faults that prevent proper operation of thevehicle, or can lead to unexpected or unintended, and therefore,dangerous operation of the vehicle.

When an existence of a fault becomes known, service personnel undertakea laborious effort of locating the fault. This process can involvemanually testing, with leads, individual wires, circuits, or conductorsto determine whether the fault is located therein. Given the extensiveamount of wiring, interconnections between wiring, electrical devices,and other electronic equipment present in the vehicle, the mere task ofuncovering the problem is time-consuming and expensive. This expense isadditional to the cost of repairing or replacing the faulty component,once identified.

BRIEF DESCRIPTION

In an embodiment, a system (e.g., an electrical fault location detectionsystem) includes a fault location unit and a control unit. The controlunit is configured to electrically couple the fault location unit to anelectrical system of a vehicle and to trigger the fault location unit topass an electrical signal to the electrical system. When the electricalsignal is passed to the electrical system, the fault location unitprovides information to the control unit indicative of a location of anelectrical fault in the electrical system.

In an embodiment, a method (e.g., method for detecting a location of anelectrical fault in a vehicle) includes receiving, from a power systemof a vehicle, a signal indicative of an occurrence of an electricalfault in an electrical system of the vehicle. The method also includestriggering a fault locating circuit to pass electrical signals to theelectrical system of the vehicle. In addition, the method includesreceiving, from the fault locating circuit, a signal indicative of alocation of the electrical fault in the electrical system. Further, themethod can include outputting information relating to the location ofthe electrical fault in the electrical system to at least one of anoperator of the vehicle or an entity remote from the vehicle.

In an embodiment, a system (e.g., an electrical fault location detectionsystem) includes a control unit for a vehicle and a plurality of scancircuits in the vehicle. The control unit is configured to electricallycouple the plurality of scan circuits to an electrical system of thevehicle. The control unit is further configured to trigger the pluralityof scan circuits to respectively pass a plurality of electrical signalsto the electrical system of the vehicle. Respective scan circuits of theplurality of scan circuits are respectively configured to detect apresence of an electrical fault in the electrical system based onrespective electrical signals of the plurality of electrical signals.The respective scan circuits are further configured to provideinformation indicative of a location of the electrical fault in theelectrical system, when detected, to the control unit.

In an embodiment, a system (e.g., an electrical fault location detectionsystem) includes a fault location unit/system having plural scancircuits that are respectively electrically connected to pluralelectrical circuits in an electrical system of a vehicle and configuredto apply respective electrical signals to the plural electricalcircuits. The system further includes a control unit configured forelectrical communication with the plural scan circuits in the vehicle.The plural scam circuits are further configured to receive secondarysignals respectively generated by the plural electrical circuitsresponsive to the electrical signals applied by the plural scan circuitsto the plural electrical circuits, and to communicate information of thesecondary signals that are received to the control unit. The controlunit is configured to determine a location of an electrical fault in theelectrical system based on the information received from the plural scancircuits. The control unit is further configured to control at least oneelectronic device based on the location of the electrical fault that isdetermined.

In an embodiment, a system (e.g., an electrical fault location detectionsystem) includes at least one scan circuit on board a vehicle, a controlunit, and a coupling circuit on board the vehicle. The coupling circuitis electrically connected to the at least one scan circuit and to pluralelectrical circuits of an electrical system of the vehicle. The controlunit is configured to control the coupling unit to selectivelyelectrically couple the at least one scan circuit to the pluralelectrical circuits. The at least one scan circuit is configured, whenelectrically coupled to the electrical circuits, to apply respectiveelectrical signals to the plural electrical circuits and to receivesecondary signals respectively generated by the plural electricalcircuits responsive to the electrical signals. The at least one scancircuit is further configured to communicate information of thesecondary signals that are received to the control unit. The controlunit is configured to determine a location of an electrical fault in theelectrical system based on the information received from the at leastone scan circuit. The control unit is further configured to control atleast one electronic device based on the location of the electricalfault that is determined.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference is made to the accompanying drawings in which particularembodiments and further benefits of the invention are illustrated asdescribed in more detail in the description below, in which:

FIG. 1 illustrates a schematic block diagram of an exemplary,non-limiting embodiment of a fault location system for a vehicleaccording to one or more aspects;

FIG. 2 illustrates a schematic block diagram of an exemplary,non-limiting embodiment of a control unit for a vehicle in accordancewith one or more aspects;

FIG. 3 illustrates a schematic block diagram of an exemplary,non-limiting embodiment of vehicle components according to one or moreaspects;

FIG. 4 illustrates a schematic block diagram of an exemplary,non-limiting embodiment of a fault location unit for a vehicle;

FIG. 5 illustrates a schematic block diagram of an exemplary,non-limiting embodiment of a scan circuit according to one or moreaspects;

FIG. 6 illustrates a block diagram of an exemplary, non-limitingembodiment of a scan circuit schematically depicting structural andfunctional aspects of the scan circuit;

FIG. 7 illustrates a block diagram of an exemplary, non-limitingembodiment of a scan circuit schematically depicting structural andfunctional aspects of the scan circuit;

FIG. 8 illustrates a block diagram of an exemplary, non-limitingembodiment of a fault location unit for a vehicle in accordance with oneor more aspects;

FIG. 9 illustrates a flow diagram of an exemplary, non-limitingembodiment of a method for locating a fault within an electrical systemof a vehicle according to one or more aspects;

FIG. 10 illustrates a flow diagram of an exemplary, non-limitingembodiment of a method for identifying a location of a fault within anelectrical system of a vehicle according to one or more aspects;

FIG. 11 is a wiring schematic of a fault location system, according toan embodiment; and

FIG. 12 is a wiring schematic of a fault location system, according toan embodiment.

DETAILED DESCRIPTION

Embodiments described herein generally relate to systems and methods forlocating an electrical fault in an electrical system of a vehicle. Thevehicle can include an extensive amount of wiring running throughout. Inaddition to the wiring, the vehicle can also include numerous electricalinterconnections, control lines, electrical devices, and/or otherelectronic devices that can be further a cause of the electrical fault.Conventionally, narrowing down a location of the electrical fault caninvolve manually testing individual components (e.g., wire,interconnections, device, etc.) separately to pinpoint the culprit. Inorder to test the components, service personnel generally gain physicalaccess. Accordingly, to merely locate a source of the electrical fault,portions and/or components of the vehicle are disassembled to enable thetest.

Fault locating systems and methods described herein reduce manual andlaborious efforts to identify a source of an electrical fault in avehicle. In addition, the fault locating systems and methods hereingenerally eliminate gaining physical access prior to performing anactual repair of a faulty component. Accordingly, overall service timefor electrical faults is reduced.

As utilized herein, the term “vehicle” refers to any transportationsystem including, but not limited to, motor vehicles (e.g., motorcycles,automobiles, trucks, busses, traction vehicles, etc.) for transport onground, watercraft (e.g., boats, ships) for transport on water, aircraft(e.g., planes, rotorcrafts) for transport in air, and/or spacecraft fortransport outside an atmosphere. “Traction vehicles”, as utilizedherein, can refer to rail vehicles such as locomotives, off-highwayvehicles, transit vehicles, or the like. Given this broad usage of theterm “vehicle”, it is to be appreciated that, as utilized herein, avehicle can be a single-compartment, permanently-arranged transportationsystem or a multiple-compartment, variably-arranged transportationsystem. Accordingly, the use of “vehicle” herein is intended toencompass transportation systems, capable of mobility on or through avariety of media, that include one or more compartments, which arerespectively interchangeable, detachable, removable, etc., such that acombination of such compartments is considered a “vehicle”.

According to one or more aspects, a vehicle can include a control unitfor monitoring and controlling various vehicle components. The controlunit can be, for example, a microprocessor-based device having aprocessor and a memory for storing data and/or programs executed by theprocessor. The control unit can further include user interface devicesto enable interactions with an operator of the vehicle and acommunication device to enable communications with off-board devices orentities.

As utilized herein, the terms “controller”, “control unit”, “controlsystem”, or “control device” are used broadly herein and refer toanything from a simple switching device, to one or more processorsrunning computer-executable software instructions, to complexprogrammable and/or non-programmable logic circuitry. Moreover, theterms “signal”, “data”, and “information” can be used interchangeablyherein and, further, can be in digital or analog form. The terms“software”, “computer program”, or “program” include, but are notlimited to, one or more computer-readable and/or executable instructionsthat cause a computer or other electronic device to perform functions,actions, and/or behave in a desired manner. It will be appreciated byone of ordinary skill in the art that a form of software is dependenton, for example, requirements of a desired application, an environmentthe software executes in, and/or desires of a designer/programmer. Theterms “computer”, “processing device”, “computing device”, or“processor”, as used herein, includes, but are not limited to, anyprogrammed or programmable device that can store, retrieve, and processdata. “Non-transitory computer-readable media” include, but are notlimited to, a CD-ROM, a removable flash memory card, a hard disk drive,a magnetic tape, and a floppy disk. “Computer memory” or “memory”, asused herein, refers to a storage device configured to store digital dataor information which can be retrieved by a computer or processingelement.

In a further aspect, the vehicle can further include a power systemhaving a power supply for providing electrical power to an electricalsystem of the vehicle. The power supply can include batteries, engines,generators, alternators, etc. that separately or jointly provide powerto the electrical system. In this regard, the vehicle can includewiring, interconnections, and the like to couple the control unit tovehicle components for control and monitoring, but the vehicle can alsoinclude wiring, interconnections, and the like to couple the powersupply to vehicle components for provisioning electrical power.

Herein, interconnections or wiring associated with control or datasignals (i.e., the control system) can be described as separate frominterconnections or wiring supplying electrical power (i.e., theelectrical system or power system). However, it is to be appreciatedthat, since the power driving the control or data signals of the controlsystem is derived from the power supply, the control system (and thewiring and interconnections therein) are considered to be a portion ofthe electrical system. The separate description of the control systemfrom the power system is provided for convenience to describe modifiedtechniques applicable to a control environment. Accordingly, exceptwhere explicitly described as applicable to the control system, thestructures and techniques described herein with regarding to theelectrical system of the vehicle are employable with the wiring,interconnections, and devices of the control system.

As utilized herein, a “vehicle component” can refer to substantially anyelectrical or electronic component installed or included in a vehicle.For control aspect, a vehicle component can be any device having anembedded control unit, or the embedded control unit. However, vehiclecomponents can also include mechanical and/or electrical components,without embedded control or considered separate from associated embeddedcontrol units, such as engines, generators, alternators, electricalsupply components (e.g., batteries), gauges, meters, communicationequipment, lighting, sensors, switches, wiring harnesses, etc. By way ofexample, in the case of a traction vehicle, vehicle components caninclude generators, alternators, rectifiers, engines, turbo chargers,cooling blowers, dynamic braking grids, inverters, converters, tractionmotors, etc. However, it is to be appreciated that vehicle components,as utilized herein, is not limited to the aforementioned enumeratedexamples and is intended to encompass any electrical or electroniccomponents of a vehicle which draw power from the power supply and/orcan be controlled via the control unit.

In one or more embodiments, a fault location unit of a vehicle (whichcan be controlled or driven by a control unit of the vehicle in someembodiments) is provided to locate an electrical fault within anelectrical system (or control system) of the vehicle. As utilizedherein, the term “electrical fault” refers to a diversion of currentalong an unintended path. For instance, a diversion of current from asource path (e.g., positive or hot) to a return path (e.g., negative orneutral) is a short. A diversion of current to ground is a ground fault.These types of faults can also be referred to as “leakage currents”.

The fault location unit can pass one or more electrical signals to theelectrical system, and on the basis of those electrical signals,identify a location of the electrical fault with in the electrical.Depending on a distribution of the electrical signals passed to theelectrical system, the location identified can specify a particularcircuit, cable, wire harness, vehicle component, vehicle system, or anindividual wire or interconnect. The electrical signals can originate(i.e., generated by) from circuits of the fault location unit.Alternatively, the electrical signals can be provided to the faultlocation unit from the control unit, for example. The electricalsignals, when applied to the electrical system, generate secondarysignals, which can be analyzed to determine the location of theelectrical fault. The secondary signals can be return signals orreceived signals, which represent the originally passed signals asmodified by electrical paths of the electrical system. The secondarysignals, under normal conditions, exhibit a predetermined behavior. Thepresence of the electrical fault causes deviations from thepredetermined behavior that can be detected from measurements of thesecondary signals. Accordingly, depending on a position, within theelectrical system, where a secondary signal is measured and a positionwhere a corresponding applied signal is passed, the location of theelectrical fault is determined.

The fault location unit can include one or more scan circuitsrespectively configured to apply an electrical signal to a portion ofthe electrical system, i.e., an electrical path of the electricalsystem. The electrical path, according to one or more aspects, can be aparticular circuit, a particular length of wire, a cable including aplurality of individual wires, a wire harness, or a sub-system orsub-network of the electrical system. A secondary signal, received fromor modified by the electrical path, can be returned to the scan circuit.According to one example, the scan circuit can include an evaluationcircuit to compare the secondary signal to the applied signal (or someother reference) to determine a difference. When the difference exceedsa threshold, unintended diversion of current can be a cause.Accordingly, when the threshold is exceeded, the scan circuit emits adetection signal indicating a presence of an electrical fault on theelectrical path. In another example, the secondary signal can beprovided to the control unit for evaluation.

The scan circuit can include a pair of circuits or cells, where a firstcell applies the signal to the electrical path and the second cellreceives the return, response, or secondary signal. The first cell andthe second cell can jointly operate to implement the evaluation circuit.Alternatively, the second cell can include a dedicated circuitimplementing the evaluation functionality.

In an aspect, the fault location unit can include a plurality of scancircuits which are designated to predetermined portions or electricalpaths of the electrical system. In this regard, an identity of theparticular scan circuit that reports detection of the electrical faultprovides the location information. Again, depending on a number of scancircuits provided and a level to which the electrical system ispartitioned or segmented for the purposes of assignment to scancircuits, the location information can be provided at a sub-systemlevel, a circuit level, a cable level, or an individual wire orinterconnect level. For example, a scan circuit can be provided to eachwire or interconnect of the electrical system. Alternatively, one ormore scan circuits can be selectively, and separately, coupled todifferent wires, circuits, or interconnects so as cycle and test eachindividually.

The fault location unit, and particularly the scan circuits thereof, canbe isolated from the electrical system when not in use. A couplingcircuit can maintain the fault location unit in isolation until theelectrical fault occurs. At that time, the coupling circuit canelectrically couple the fault location unit to the electrical system toenable operation. As utilized herein, the term “electrically couple”refers to establishing a connection that enables at least one ofinformation or a signal to pass, either with or without any sort ofphysical coupling or contact.

According to an additional aspect, the power supply can include a sensorconfigured to detect an occurrence of the electrical fault within theelectrical system as a whole. This information can be provided to thecontrol unit for initiation of self-testing (i.e., self-locating) forthe electrical fault. Further, the control unit can display a warning orother information related to the electrical fault on a display devicefor an operator of the vehicle. The control unit can signal for thefault location unit to be coupled to the electrical system and, further,can trigger the fault location unit to begin diagnosing the electricalsystem. The fault location unit can be triggered in response to a userinput received from the operator via a user interface.

Prior to triggering the fault location unit, the control unit candetermine whether the vehicle is in a safe state. As utilized herein, a“safe state” is any state of the vehicle in which spurious signals,currents, or voltages applied to the electrical system are tolerated andwill not cause a dangerous situation or result. By way of example, whilein a safe state, the vehicle will not behave erratically or unexpectedlyshould the signal applied by the fault location unit be interpreted as athrottle signal, for example. Safe states can include an idle state, astationary state, a tie-down state (i.e., brakes applied), adisassembled or pre-assembly state, or the like.

The control unit, once provided with information related to the locationof the electrical fault, can output such information to the displaydevice and/or communicate the information to an entity remote from thevehicle. As utilized herein, “an entity remote from the vehicle” can bea computing device which is not physically or electrically coupled tothe vehicle. As utilized herein, the entity is not intended to belimited to being geographically or physical remote from the vehicle. Forinstance, in one embodiment, the entity can be a mobile device carriedby the operator or other service personnel aboard the vehicle. In otherembodiments, the entity can be a computing device at a service location,a storage location, or some other vehicle station.

According to one embodiment, a system for locating electrical faults isdescribed. The system includes a fault location unit and a control unit.The control unit is configured to electrically couple the fault locationunit to an electrical system of a vehicle and to trigger the faultlocation unit to pass an electrical signal to the electrical system.When the electrical signal is passed to the electrical system, the faultlocation unit provides information to the control unit indicative of alocation of an electrical fault in the electrical system.

According to one example, the system can include a sensor for detectingan occurrence of the electrical fault in the electrical system. Thesensor is configured to send a signal indicative of the occurrence ofthe electrical fault to the control unit when detected. The systemfurther includes a power supply configured to provide electrical powerto the electrical system of the vehicle. The sensor can be coupled tothe power supply.

In another example, the control unit is configured to verify the vehicleis in a safe state prior to electrically coupling the fault locationunit to the electrical system. According to another example, the systemincludes a coupling circuit configured, in a first mode of operation, toselectively couple the fault location unit to the electrical system, andin a second mode of operation to isolate the fault location unit fromthe electrical system.

According to one example, the fault location unit includes a scancircuit configured to pass a signal to an electrical path of theelectrical system to detect a presence of the electrical fault in theelectrical path to which the scan circuit is coupled. The scan circuitcan include an evaluation circuit to compare the signal transmitted onthe electrical path to a signal later received on the electrical path.The evaluation circuit is configured to output a detection signal when adifference in the signal transmitted and the signal received exceeds athreshold.

The scan circuit, according to some examples, includes a first cell anda second cell. The first cell is configured to pass the electricalsignal on the electrical path and the second cell is configured toreceive the electrical signal on the electrical path. In one example,the electrical path can be a circuit such that the first cell transmitsthe electrical signal on a first wire and the second cell receives theelectrical signal on a second wire that completes the circuit. Inanother example, the electrical path is a length of wire such that thefirst cell transmits the electrical signal on the length of wire to thesecond cell.

The fault location unit can be configured to individually and cyclicallycouple the scan circuit to a plurality of portions of the electricalsystem to test each portion for the electrical fault.

Further, the control unit can include a user interface device having atleast a display device configured to display information to an operatorof the vehicle and a communication interface configured to communicatewith an entity remote from the vehicle. The control unit can beconfigured to at least one of output the information indicative of thelocation of the electrical fault in the electrical system to the displaydevice, or transmit the information, via the communication interface, toan entity remote from the vehicle.

According to another embodiment, a method for locating an electricalfault is described. The method includes receiving, from a power systemof a vehicle, a signal indicative of an occurrence of an electricalfault in an electrical system of the vehicle. The method also includestriggering a fault locating circuit to pass electrical signals to theelectrical system of the vehicle. In addition, the method includesreceiving, from the fault locating circuit, a signal indicative of alocation of the electrical fault in the electrical system. Further, themethod includes outputting information relating to the location of theelectrical fault in the electrical system to at least one of an operatorof the vehicle or an entity remote from the vehicle.

In accordance with an example, the method can further includeelectrically coupling the fault locating circuit to the electricalsystem of the vehicle in response to the signal indicative of theoccurrence of the electrical fault from the power system, and otherwiseisolating the fault locating circuit from the electrical system. Infurther examples, the method can include determining a state of thevehicle, and verifying the state of the vehicle is a safe state prior totriggering the fault locating circuit.

In yet another example, the method can include passing a signal to anelectrical path of the electrical system to detect a presence of theelectrical fault in the electrical path. In addition, the methodincludes comparing the signal transmitted on the electrical path to asignal received on the electrical path, determining when a difference inthe signal transmitted and the signal received exceeds a threshold, andissuing the signal indicative of the location of the electrical faultwhen the threshold is exceeded. The location indicated by the signalspecifies the electrical path.

In yet another embodiment, a system is described that includes a controlunit for a vehicle and a plurality of scan circuits in the vehicle. Thecontrol unit is configured to electrically couple the plurality of scancircuits to an electrical system of the vehicle and trigger theplurality of scan circuits to respectively pass a plurality ofelectrical signals to the electrical system of the vehicle. Moreover,respective scan circuits of the plurality of scan circuits arerespectively configured to detect a presence of an electrical fault inthe electrical system based on respective electrical signals of theplurality of electrical signals. The respective scan circuits arefurther configured to provide information indicative of a location ofthe electrical fault in the electrical system, when detected, to thecontrol unit.

According to an example of the foregoing embodiment, respective scancircuits of the plurality of scan circuits respectively comprise a pairof circuits configured to pass a test signal to a designated portion ofthe electrical system and receive a response signal from the designatedportion of the electrical system. The pair of circuits output adetection signal to the control unit when a difference between the testsignal and the response signal exceeds a threshold. The control unitdetermines the location of the electrical fault based on the designatedportion of the electrical system associated with the pair of circuitswhich output the detection signal.

With reference to the drawings, like reference numerals designateidentical or corresponding parts throughout the several views. However,the inclusion of like elements in different views does not mean a givenembodiment necessarily includes such elements or that all embodiments ofthe invention include such elements.

Turning to FIG. 1, illustrated is a schematic block diagram of anexemplary, non-limiting embodiment of a fault location system for avehicle 100. In the embodiment, the vehicle 100 includes a control unit110 for controlling and monitoring vehicle components 140 via a controlpath 160. As shown in FIG. 2, the control unit 110 includes a processor112, a memory 114, a user interface 116, a communication interface 118,and an I/O interface 119. The user interface 116 can include a displaydevice 115 to output information to an operator of the vehicle and aninput device 117 to obtain information from the operator. The displaydevice 115 can be a display screen, a segment display, a series ofgraphical elements which can be illuminated, gauges, meters, or thelike. The input device 117 can include keyboards, pointing devices,buttons, switches, knobs, dials, or the like. It is to be appreciatedthat the display device 115 and the input device 117 can be containedwithin a single device, e.g. touch screen, such that user interface 116comprises a graphical user interface generated by the processor 112based on computer-executable instructions (e.g., a control application)stored on memory 114.

In an aspect, the control unit 110 can communicate via a wired orwireless medium. For instance, the communication interface 118 canenable the control unit 110 to communicate via a cable, e.g., USB cable,serial cable, Ethernet cable, or the like. In another example, thecommunication interface 118 provides wireless communications via WiFi(e.g., IEEE 802.11), cellular radio (e.g., GSM, LTE, CDMA, HSPA, UMTS,WiMAX, etc.), satellite communication, near-field communication,infrared, a short-range radio frequency (RF) protocol such as Bluetooth,or substantially any other wireless communication technology.

The I/O interface 119 includes the external connectors to couple thecontrol unit 110 to the control path 160 to enable communication withvehicle components 140. The I/O interface 119 further includes theinternal interconnections, adapters, and circuits to couple to processor112. The I/O interface 119 can transform signals or data from a formatsuitable for processing by the control unit 112 to a format suitable fortransmission via the control path 160 and/or a format suitable forconsumption by the vehicle components 140. Likewise, the I/O interface119 can perform a complementary transformation on incoming data orsignals.

Turning briefly to FIG. 3, vehicle components 140 can include one ormore individual vehicle components 142 (depicted as vehicle components142 ₁ through 142 _(N), where N is any integer greater than or equal toone), such as various electrical, mechanical, or control components.Each vehicle component 142 can include a corresponding component controlunit 144, which is an endpoint on the control path 160 forcommunications with the control unit 110.

Turning back to FIG. 1, the vehicle 100 also includes a power supply 120for providing electrical power to an electrical system 130 via anelectrical supply path 170. As described above, the electrical system130 and the electrical supply path 170 can encompass, in someembodiments, the control path 160, the vehicle component 140, and thewires, interconnections, etc. of the control path 160. That is, whendiscussing the electrical system 130, it is intended to include thecontrol path 160 and the vehicle components 140, unless explicitlystated otherwise.

As shown in FIG. 1, a sensor 122 is provided for detecting an occurrenceof an electrical fault in the electrical system 130. According to oneexample, the sensor 122 can be coupled to or included in the powersupply 120. The sensor 122 can register a voltage drop, for example, ormeasure a return current to determine whether any unintended diversionof current is occurring within the electrical system 130. Once theelectrical fault is detected, the sensor 122 can send a signal to thecontrol unit 110.

The control unit 110, in response to the signal from the sensor 122, canoutput a notification of the electrical fault to the user interface 116and initiate a self-testing routine to locate the electrical fault.According to one example, the self-testing can commence autonomouslyupon receiving the signal from sensor 122. In another example, userinput via user interface 116 is received to begin self-testing.

To initiate self-testing, the control unit 110 electrically couples afault location unit 150 to the electrical system 130. For instance, thecontrol unit 110 can pass signals to coupling circuits 180, 190 toelectrically couple the fault location unit 150 to the electrical supplypath 170 and/or the control path 160, thereby attaching the faultlocation unit 150 to the electrical system 130. The coupling circuits180, 190, according to an aspect, are configured to electrically isolatethe fault location unit 150 from the electrical system 130 except whenthe signal is passed from the control unit 110.

Once coupled, the fault location unit 150 can be brought on-line by thecontrol unit 110. Once activated, the fault location unit 150 can applyelectrical signals to the electrical system 130 to identify a locationof the electrical fault therein. Once identified, the fault locationunit 150 provides location information to the control unit 110. Thelocation information can be displayed on a display screen of the userinterface 116 and/or transmitted to an entity remote from vehicle 100via communication interface 118.

Prior to triggering the fault location unit 150, the control unit 110can determine a state of the vehicle 100. For instance, the control unit110, via the control path 160, can interrogate vehicle components 140 toascertain current statuses thereof. In another example, the control unit110, which can receive regular streams of information from vehiclecomponents 140, can determine the state based on data stored on memory114 or some other non-transitory, computer-readable media. In addition,the control unit 110 can determine state the based on a snapshot of astream of data. Once the state of vehicle 100 is identified, the controlunit 100 triggers the fault location unit 150 when the vehicle is in asafe state.

Turning to FIG. 4, illustrated is a schematic block diagram of anexemplary, non-limiting embodiment of the fault location unit 150. Asshown in FIG. 4, the fault location unit 150 can include one or morescan circuits 152 (depicted as scan circuit 152.sub.1 through scancircuit 152.sub.N, where N is any integer greater than or equal to one).Each scan circuit 152 can be configured to receive a trigger signal 154,from control unit 110 for example, which initiates a test procedure forat least a portion of the electrical system 130.

For the test procedure, the scan circuit 152 applies a test signal 156to an electrical path 400 of the electrical system 130. The electricalpath 400 can be an individual wire, an individual electrical component,a circuit, a portion of a circuit, a sub-system, or the like. Inresponse, the scan circuit 152 receives a secondary signal or returnsignal 157, which represents the test signal 156 as modified by theelectrical path 400. Scan circuit 152 can evaluate the return signal 157to determine whether the electrical fault is present on the electricalpath 400. If so, the scan circuit 152 sends a detection signal 155 tothe control unit 110.

According to an aspect, each scan circuit 152 can be associated with aparticular respective portion of the electrical system 130 (e.g., aparticular wire, interconnection, circuit or portion thereof). As such,the detection signal 155 is indicative of a location of the electricalfault, since the detection signal 155 from a given scan circuit 152indicates the electrical fault is located in the portion of theelectrical system 130 associated therewith.

FIG. 5 illustrates a schematic block diagram of an exemplary,non-limiting embodiment of the scan circuit 152 according to one or moreaspects. The scan circuit 152 can include a pair of circuits 158, 159,which are also referred to herein as a first cell 158 and a second cell159. The pair of circuits 158, 159 are configured to pass test signal156 to a designated electrical path of the electrical system 130,receive the return signal 157 from the electrical path, and evaluate thereturn signal 157 to determine whether the electrical fault is locatedon the electrical path.

First cell 158 can receive the trigger signal 154 from the control unit110 and, in response, apply the test signal 156 to the electrical path.According to one example, the test signal 156 can be generated by thecircuit implementing the first cell 158. In another example, the controlunit 110 can generate the test signal 156 and the first cell 158 canpass the test signal 156 through to the electrical path. For instance,the trigger signal 154 can be the test signal 156, with or withoutmodification by the first cell 158.

Second cell 159 can receive the secondary or return signal 157 from theelectrical path. The second cell 159, in an aspect, can include anevaluation circuit which analyzes the return signal 157 to determinewhether the electrical fault exists on the electrical path. In oneexample, the evaluation circuit can compare the test signal 156 to thereturn signal 157 to determine a difference. The difference can bemeasured against a threshold that, when exceeded, triggers the secondcell 159 to emit the detection signal 155. According to another example,the second cell 159 can merely pass through the return signal 157 to thecontrol unit 110, which evaluates the signal to determine whether theelectrical fault exists on the electrical path associated with the scancircuit 152. For instance, a diagnostic application or program stored onmemory 114 can be executed by processor 112 to generate trigger signal154 (and/or test signal 154) and analyze detection signal 155 (and/orreturn signal 157).

Depending on the electrical path being tested, the first cell 158 andthe second cell 159 can be implemented in a variety of manners providingdifferent structural or functional aspects. Moreover, in the case of anelectrical path associated with the control path 160, at least one ofthe first cell 158 or the second cell 159 can be associated with,coupled to, or included in the component control unit 144.

Turning to FIG. 6, illustrated is a block diagram of an exemplary,non-limiting embodiment of a scan circuit 600 for testing a wire orinterconnection, according to an aspect. The scan circuit 600 includes asource cell 602 and a target cell 604 electrically coupled by a wire orinterconnection 606. The source cell 602 applies a signal 608 (i.e., atest signal) to the wire 606, which is received by the target cell 604.The signal 608 can be evaluated by the target cell 604, or passed to acontrol system for evaluation, to determine whether an electrical faultis present along wire 606.

In an example, the source cell 602 can be associated with the faultlocation unit 150 or control unit 110 and the target cell 604 can beassociated with the component control unit 144. The source cell 602 canbe positioned at one terminal or boundary of the wire 606, which can be,for example, physically proximal to the control unit 110 or power supply120. The target cell 604 can be positioned at another terminal orboundary of the wire 606 at a location physically remote from thecontrol unit 110 or power supply 120.

FIG. 7 illustrates a block diagram of an exemplary, non-limitingembodiment of a scan circuit 700 for testing a circuit for an electricalfault, according to an aspect. Scan circuit 700 is electrically coupledto a circuit or load 702 having a positive or hot wire 704 and anegative or neutral wire 706. Scan circuit 700 includes a first cell 708that applies a first signal 712 on the positive wire 704 and a secondcell 710 that receives a second signal 714 on the negative wire 706. Thesecond signal 714 can be analyzed to determine whether an electricalfault is present in the circuit or load 702, positive wire 704, ornegative wire 706.

FIG. 8 illustrates a block diagram of an exemplary, non-limitingembodiment of a fault location unit 800 unit for a vehicle 100 inaccordance with one or more aspects. Fault location unit 800 includes ascan circuit 802 and a selector 804. It is to be appreciated that scancircuit 802 can be substantially similar to and perform substantiallysimilar functionality as scan circuits 152, 600, or 700 described above.

Scan circuit 802 is coupled to an input of selector 804, which can be amultiplexor or other routing circuit configured to selectively couplethe input to one of a plurality of outputs. The output of the pluralityof outputs is determined by a select signal 806. The select signal 806can be generated by the fault location unit 800 itself, or externallyprovided by control unit 110 for example. The plurality of outputs ofselector 804 are respectively coupled, electrically, to one or moreportions or electrical paths 808 of the electrical system 130(designated as electrical path 808.sub.1 through electrical path808.sub.N, where N is any integer greater than or equal to one). Byvarying the select signal 806, the fault location unit 800 can cyclethrough the electrical paths 808 and test each one, individually, withscan circuit 802.

In view of the exemplary devices and systems described supra,methodologies that can be implemented in accordance with the disclosedsubject matter are described with reference to the flow charts of FIGS.9 and 10. The methodologies are shown and described as a series ofblocks; however, the claimed subject matter is not limited by the orderof the blocks, as some blocks can occur in different orders and/orconcurrently with other blocks. Moreover, not all illustrated blocks maybe required to implement the methods described hereinafter. Themethodologies can be implemented by the system described above withrespect to FIGS. 1-8, for example.

FIG. 9 illustrates a flow diagram of an exemplary, non-limitingembodiment of a method for locating a fault within an electrical systemof a vehicle according to one or more aspects. At 900, a signalindicating an occurrence of an electrical fault in a vehicle isreceived. The signal can be generated by a sensor, for example, coupledto a power supply of the vehicle. At 910, it is verified that thatvehicle is in a safe state. A control until of the vehicle, based oninformation or signals from various vehicle components, can determine astate of the vehicle. At 920, a fault locating circuit is triggered. Inan example, the fault locating circuit can be electrically isolated fromthe electrical system of the vehicle, but electrically coupled to theelectrical system in response to the signal received at 900. At 930, asignal is received from the fault locating circuit. The signal indicatesa location of the electrical fault in the electrical system of thevehicle. At 940, the information related to the location of theelectrical fault is output. For example, the information can be outputto a display screen of a user interface or communicated, via acommunication interface, to an entity remote from the vehicle.

FIG. 10 illustrates a flow diagram of an exemplary, non-limitingembodiment of a method for identifying a location of a fault within anelectrical system of a vehicle according to one or more aspects. At1000, a signal is applied to a first electrical path. According to anexample, the signal is provided by a scan circuit having a pair ofcells, which is designated to the first electrical path. At 1010, areturn signal is received on a second electrical path. It is to beappreciated that the first and second electrical paths can be a samepath, or different paths. For example, when testing an individual lengthof wire, the first and second paths can be the same individual length ofwire. Alternatively, when testing the individual length, the firstelectrical path can be the length of wire, while the second electricalpath is another wire, wires, or circuit. Further still, when testing acircuit, for example, the first path can be a first set of wires (e.g.,one or more wires) and the second path can be a second set of wires(e.g., one or more wires) that completes the circuit. In some embodimentor examples, the second electrical path can be known to be fault-free,such that the first electrical path is the portion under test. At 1020,it is determined, on the basis of the return signal, whether anelectrical fault is present on the electrical path (e.g., either thefirst electrical path or second electrical path). For example, thesignal applied and the return signal can be compared to determinewhether a difference therebetween exceeds a threshold. At 1030, whendetermined that an electrical fault is present (e.g., the threshold isexceeded), a detection signal is output. It is to be appreciated thatcomputing a difference signal and comparing said signal to a thresholdis one exemplary technique to detect an electrical fault. Othertechniques are applicable and are contemplated within the bounds of theclaimed subject-matter unless explicitly detailed otherwise.

FIG. 11 shows a wiring schematic of an embodiment of the fault locationsystem. In particular, as illustrated, for each circuit of interest 400(e.g., each circuit may be a wire loop/circuit) in the vehicleelectrical system, a separate and distinct scan circuit 152 a, 152 b,152 c, 152 d, etc. is respectively connected to the circuit 400, e.g.,in parallel. That is, in this embodiment, there is a scan circuit foreach wire or other circuit portion of interest. In a given vehicleelectrical system, this may mean the provision of hundreds or thousandsof scan circuits. However, with mass produced, low costmicro-electronics currently available on the market, implementations onsuch a scale may nevertheless be practicable. Also, as should beappreciated, the scan circuits can be built into the electrical panels,circuit boards, etc. 200 to which the wire loops or other circuits arepart of and/or electrically coupled, keeping implementation costsrelatively low.

FIG. 12 shows a wiring schematic of another embodiment of the faultlocation system. Here, the system includes one scan circuit 152 and apair of selector units (e.g., multiplexers) 804 a, 804 b. The controlunit 110 is configured to control the selector units 804 a, 804 b, onefor selectively connecting the out path of each circuit 400 to the scancircuit and the other for selectively connecting the in path of eachcircuit to the scan circuit. The scan circuit is cyclically connected tothe circuits for testing each in turn.

In an embodiment, a system (e.g., an electrical fault location detectionsystem) includes plural scan circuits respectively electricallyconnected to plural electrical circuits in an electrical system of avehicle and configured to apply respective electrical signals to theplural electrical circuits. The system further includes a control unitconfigured for electrical communication with the plural scan circuits inthe vehicle. (The control unit may be located off board the vehicle, inwhich case the control unit may be configured to wirelessly communicatewith the scan circuits on board the vehicle; in one embodiment, however,the control unit is located on board the vehicle and is electricallyconnected to the scan circuits either wirelessly or with wires.) Theplural scan circuits are further configured to receive secondary signalsrespectively generated by the plural electrical circuits responsive tothe electrical signals applied by the plural scan circuits to the pluralelectrical circuits, and to communicate information of the secondarysignals that are received to the control unit. The control unit isconfigured to determine a location of an electrical fault in theelectrical system based on the information received from the plural scancircuits. The control unit is further configured to control at least oneelectronic device based on the location of the electrical fault that isdetermined.

For example, in an embodiment, the at least one electronic device thatthe control unit is configured to control comprises (i) a display deviceof a user interface of the vehicle, for display of the location of theelectrical fault in the electrical system, and/or (ii) a communicationdevice, for communication of the location of the electrical fault in theelectrical system to a device off board the vehicle. In anotherembodiment, the at least one electronic device that the control unit isconfigured to control comprises a vehicle system on board the vehicle.For example, the control unit may be configured to control theelectrical system of the vehicle, an engine of the vehicle or anothercomponent of a propulsion system of the vehicle, etc., for operationfrom a first state to operation in a different, second state, such asthe vehicle being brought from moving along a route to a stoppedcondition, or the electrical system (or portion thereof) beingtransitioned from an on or operational state to an off or non-operatingstate.

In an embodiment, the control unit is further configured to generatecontrol signals for communication to the plural scan circuits, and thescan circuits are configured to apply the electrical signals to theplural electrical circuits responsive to the control signals.

In an embodiment, the system further includes a sensor configured todetect an occurrence of the electrical fault in the electrical system.The sensor is further configured to send a signal indicative of theoccurrence of the electrical fault to the control unit when detected,and the control unit is configured to generate the control signalsresponsive to receipt of the signal indicative of the occurrence of theelectrical fault. For example, the vehicle may include a power supplyconfigured to provide electrical power to the electrical system of thevehicle, and in such an instance the sensor may be coupled to the powersupply for detecting the electrical fault based on a change inelectrical power output by the power supply (for example).

In an embodiment, the scan circuits are configured to be selectivelyelectrically coupled to the plural electrical circuits, and toelectrically couple to the plural electrical circuits responsive to thecontrol signals. For example, the scan circuits may be connected to thevehicle electrical circuits by respective switches, which the controlunit is configured to control with the control signals. In anembodiment, the control unit is configured to verify the vehicle is in adesignated operational state (e.g., a safe state, such as stopped at adesignated location) as a condition precedent for generating the controlsignals to electrically couple the scan circuits to the electricalsystem.

In an embodiment, the system further includes a coupling circuit (e.g.,one or more multiplexer circuits) configured, in a first mode ofoperation under control of the control unit, to selectively couple thescan circuits to the electrical system, and in a second mode ofoperation under control of the control unit to isolate the scan circuitsfrom the electrical system.

In an embodiment, the scan circuit includes an evaluation circuit thatis configured to determine a comparison of the respective one of theelectrical signals applied to the electrical circuit (the electricalcircuit to which the scan circuit is electrically connected) to arespective one of the secondary signals generated by the electricalcircuit responsive to the respective one of the electrical signalsapplied to the electrical circuit, and the evaluation circuit may beconfigured to output a detection signal based on the comparison, thedetection signal including the information communicated to the controlunit.

In an embodiment, the scan circuit further includes a first cell and asecond cell. The first cell is configured to apply the respective one ofthe electrical signals to a first wire of the electrical circuit. Thesecond cell is configured to receive the respective one of the secondarysignals on a second wire of the electrical circuit that completes theelectrical circuit.

In an embodiment, the scan circuit includes a first cell and a secondcell, and the electrical circuit comprises a length of wire. The firstcell is configured to apply the respective one of the electrical signalson the length of wire, and the second cell is configured to receive therespective one of the secondary signals on the length of wire.

In an embodiment, a system (e.g., an electrical fault location detectionsystem) includes at least one scan circuit on board a vehicle, a controlunit, and a coupling circuit (e.g., one or more multiplexer circuits) onboard the vehicle. The coupling circuit is electrically connected to theat least one scan circuit and to plural electrical circuits of anelectrical system of the vehicle. The control unit is configured tocontrol the coupling unit to selectively electrically couple the atleast one scan circuit to the plural electrical circuits. The at leastone scan circuit is configured, when electrically coupled to theelectrical circuits, to apply respective electrical signals to theplural electrical circuits and to receive secondary signals respectivelygenerated by the plural electrical circuits responsive to the electricalsignals. The at least one scan circuit is further configured tocommunicate information of the secondary signals that are received tothe control unit. The control unit is configured to determine a locationof an electrical fault in the electrical system based on the informationreceived from the at least one scan circuit. The control unit is furtherconfigured to control at least one electronic device based on thelocation of the electrical fault that is determined.

In an embodiment, a system (e.g., an electrical fault location detectionsystem) includes at least one scan circuit on board a vehicle, a controlunit, and a coupling circuit (e.g., multiplexer circuit) on board thevehicle. The coupling circuit is electrically connected to the at leastone scan circuit and to plural electrical circuits of an electricalsystem of the vehicle. The control unit is configured to control thecoupling unit to selectively electrically couple the at least one scancircuit to the plural electrical circuits. The at least one scan circuitis configured, when electrically coupled to the electrical circuits, toapply respective electrical signals to the plural electrical circuitsand to receive secondary signals respectively generated by the pluralelectrical circuits responsive to the electrical signals. The at leastone scan circuit is further configured to communicate information of thesecondary signals that are received to the control unit. The controlunit is configured to determine a location of an electrical fault in theelectrical system based on the information received from the at leastone scan circuit. The control unit is further configured to control atleast one electronic device based on the location of the electricalfault that is determined, and to control the coupling circuit toindividually and cyclically couple a single one of the at least one scancircuit to the plural electrical circuits to test each of the pluralelectrical circuits for the electrical fault. (That is, one scan circuitis connected to an individual electrical circuit for testing, and isthen disconnected from that circuit for re-connection to anotherelectrical circuit, and so on until all circuits are tested.) Further,the at least one electronic device that the control unit is configuredto control may include a vehicle system on board the vehicle.

In an embodiment, a system (e.g., an electrical fault location detectionsystem) includes at least one scan circuit on board a vehicle, a controlunit, a coupling circuit (e.g., multiplexer circuit) on board thevehicle, and a sensor configured to detect an occurrence of theelectrical fault in the electrical system. The coupling circuit iselectrically connected to the at least one scan circuit and to pluralelectrical circuits of an electrical system of the vehicle. The controlunit is configured to control the coupling unit to selectivelyelectrically couple the at least one scan circuit to the pluralelectrical circuits. The at least one scan circuit is configured, whenelectrically coupled to the electrical circuits, to apply respectiveelectrical signals to the plural electrical circuits and to receivesecondary signals respectively generated by the plural electricalcircuits responsive to the electrical signals. The at least one scancircuit is further configured to communicate information of thesecondary signals that are received to the control unit. The controlunit is configured to determine a location of an electrical fault in theelectrical system based on the information received from the at leastone scan circuit. The control unit is further configured to control atleast one electronic device based on the location of the electricalfault that is determined. The sensor is configured to send a signalindicative of the occurrence of the electrical fault to the control unitwhen detected, and the control unit is configured to control thecoupling unit to electrically couple the at least one scan circuit tothe plural electrical circuits responsive to receipt of the signalindicative of the occurrence of the electrical fault.

In the specification and claims, reference will be made to a number ofterms that have the following meanings. The singular forms “a”, “an” and“the” include plural referents unless the context clearly dictatesotherwise. Approximating language, as used herein throughout thespecification and claims, may be applied to modify a quantitativerepresentation that could permissibly vary without resulting in a changein the basic function to which it is related. Accordingly, a valuemodified by a term such as “about” is not to be limited to the precisevalue specified. In some instances, the approximating language maycorrespond to the precision of an instrument for measuring the value.Moreover, unless specifically stated otherwise, a use of the terms“first,” “second,” etc., do not denote an order or importance, butrather the terms “first,” “second,” etc., are used to distinguish oneelement from another.

As used herein, the terms “may” and “may be” indicate a possibility ofan occurrence within a set of circumstances; a possession of a specifiedproperty, characteristic or function; and/or qualify another verb byexpressing one or more of an ability, capability, or possibilityassociated with the qualified verb. Accordingly, usage of “may” and “maybe” indicates that a modified term is apparently appropriate, capable,or suitable for an indicated capacity, function, or usage, while takinginto account that in some circumstances the modified term may sometimesnot be appropriate, capable, or suitable. For example, in somecircumstances an event or capacity can be expected, while in othercircumstances the event or capacity cannot occur—this distinction iscaptured by the terms “may” and “may be.”

This written description uses examples to disclose the invention,including the best mode, and also to enable one of ordinary skill in theart to practice the invention, including making and using a devices orsystems and performing incorporated methods. The patentable scope of theinvention is defined by the claims, and may include other examples thatoccur to one of ordinary skill in the art. Such other examples areintended to be within the scope of the claims if they have structuralelements that do not differentiate from the literal language of theclaims, or if they include equivalent structural elements withinsubstantial differences from the literal language of the claims.

What is claimed is:
 1. A system comprising: a location unit configured to direct a distribution of electrical signals through different conductive pathways to several components of an electric system of a vehicle, the location unit configured to receive a modified version of one or more of the electric signals, wherein the one or more electric signals is changed into the modified version by one or more of the conductive pathways, the location unit configured to determine a location of an electric fault in the electric system based on a measurement position where the modified version of the one or more electric signals is measured and an application position where the one or more electric signals is changed into the modified version and a coupling unit under control of a control unit and configured to maintain the location unit in isolation until receipt of a signal from a sensor that the electrical fault occurs.
 2. The system of claim 1, wherein the location unit is configured to direct the distribution of the electric signals through the conductive pathways that are used to conduct control signals to the electric system of the vehicle for control of movement of the vehicle.
 3. The system of claim 1, wherein the location unit is configured to determine the location of the electric fault by comparing at least one of the electric signals in the distribution with the modified version of the one or more electric signals.
 4. The system of claim 1, wherein the location unit includes plural scan circuits each configured to direct a subset of the distribution of the electric signals into a different portion of the electric system and determine the location of the electric fault within the corresponding portion of the electric system.
 5. The system of claim 1, wherein: the coupling unit is configured to disconnect the location unit from the electric system of the vehicle based on an operating state of the vehicle.
 6. The system of claim 1, wherein: the control unit is configured to prevent the location unit from directing the distribution of the electrical signals through the conductive pathways unless the vehicle is in a state where the distribution of the electric signals does not change or cause movement of the vehicle.
 7. The system of claim 1, wherein the location unit is configured to determine the location of the electric fault as the location of an electric short.
 8. A method comprising: directing a distribution of electrical signals through different conductive pathways to several components of an electric system of a vehicle; receiving a modified version of one or more of the electric signals, wherein the one or more electric signals is changed into the modified version by one or more of the conductive pathways; determining a location of an electric fault in the electric system based on a measurement position where the modified version of the one or more electric signals is measured and an application position where the one or more electric signals is changed into the modified version; and isolating a location unit that generates the distribution of the electric signals, from the electric system of the vehicle until receipt of a signal from a sensor that the electrical fault occurs.
 9. The method of claim 8, wherein the distribution of the electric signals is directed through the conductive pathways that are used to conduct control signals to the electric system of the vehicle for control of movement of the vehicle.
 10. The method of claim 8, wherein the location of the electric fault is determined by comparing at least one of the electric signals in the distribution with the modified version of the one or more electric signals.
 11. The method of claim 8, wherein directing the distribution of electric signals into the electric system includes directing a subset of the distribution of the electric signals into each of plural, different portions of the electric system and determining the location of the electric fault within at least one of the portions of the electric system.
 12. The method of claim 8, further comprising: preventing the location unit that generates the distribution of the electric signals from generating the electric signals unless the vehicle is in a state where the distribution of the electric signals does not change or cause movement of the vehicle.
 13. The method of claim 8, wherein the location of the electric fault is determined as the location of an electric short.
 14. A system comprising: a location unit configured to direct electrical signals through different conductive pathways to several components of an electric system of a vehicle, the location unit configured to receive a modified version of one or more of the electric signals, wherein the one or more electric signals is changed into the modified version by one or more of the conductive pathways, the location unit configured to determine a location of an electric fault in the electric system based a difference between (a) at least one of the electric signals and (b) the modified version of the one or more electric signals; a control unit configured to prevent the location unit from directing the electrical signals through the conductive pathways unless the vehicle is in a state where the electric signals do not change or cause movement of the vehicle; and a coupling unit under control of the control unit and configured to maintain the location unit in isolation until receipt of a signal from a sensor that the electrical fault occurs.
 15. The system of claim 14, wherein the location unit is configured to determine the location of the electric fault also based on a measurement position where the modified version of the one or more electric signals is measured and an application position where the one or more electric signals that is changed into the modified version.
 16. The system of claim 14, wherein the location unit is configured to direct the electric signals through the conductive pathways that are used to conduct control signals to the electric system of the vehicle for control of movement of the vehicle.
 17. The system of claim 14, wherein the location unit includes plural scan circuits each configured to direct a subset of the electric signals into a different portion of the electric system and determine the location of the electric fault within the corresponding portion of the electric system.
 18. The system of claim 14, wherein the coupling unit is configured to disconnect the location unit from the electric system of the vehicle based on an operating state of the vehicle.
 19. The system of claim 14, wherein the location unit is configured to determine the location of the electric fault as the location of an electric short. 